Is too much cancer screening hazardous to your health? The example of breast cancer

From a recent speech by Peter Gøtzsche, researcher and director of the Nordic Cochrane Centre, author of “Mammography screening. Truth, lies and controversy” (Radcliffe Publishing, 2012):

"Breast cancer screening with mammography has been studied in nine randomized trials. Four of the trials are more reliable than others and these trials showed a reduction in breast cancer mortality after 13 years of 10%. The less reliable trials showed a much bigger reduction in breast cancer mortality, namely 25%. It is therefore uncertain what the true effect of screening is."

Read the full text of his speech [3].